There is a need to be able to discover any number of devices in any directly or indirectly reachable networks when they may not have any layer-2 and/or layer-3 addressing information since they do not actively participate in any of the normal network protocols in use.
Often the IDs or labels used by the protocols are not the same in both directions. If the device is not participating in the underlying protocols (e.g., MPLS, L2TPv3, GTP-U, etc.), the device (Small Form-Factor Pluggable (SFP) with a Field Programmable Gate Array (FPGA), Network Interface Device (NID), module or other platform) does not know what ID or label to use to communicate.